1. Field of the Invention
The present invention relates to an antenna, and particularly relates to a coil-shaped helical antenna.
2. Background Information
Conventionally, when helical antennas are produced, the same method is used as the one employed with springs to fashion copper wire or another metal material into a helically bent shape. Springs have poor shape retention when merely bent into shape, and are therefore usually hardened at high temperatures.
Such coil-shaped helical antennas are effectively used as small antennas, as disclosed, for example, in Japanese Laid-open Patent Publication Nos. 2001-345628 and 2006-340186.